Detonating cap safety devices

ABSTRACT

In projectiles it is desirable to prevent premature detonation of the explosive charge and therefore the detonating cap is provided in a rotor which is turned from a safety position to a detonating position by spring means after operation of a safety chain comprising several safety components including a first component comprising two interdependent inertia bolts, a second component released by the first component, and a third component constructed as a gas pressure safety device, the second and third components being operatively connected with the rotor such that premature release of one of the components blocks rotation of the rotor into the detonating position. A self-contained disc-shaped construction housing all the safety components is provided for attachment to a projectile.

nite States Backstein et a1.

[ 1 Dec. 18, 1973 DETONATHNG CAP SAFETY DEVECES Inventors: Gunter Backstein; Lothar Petzsch,

both of Meerbusch-Langst,

Germany Assignee: Rheinmetall Gmbl-i, Dusseldorf,

Germany Filed: Jan. 27, 1972 Appl. No.: 221,280

{30} Foreign Application Priority Data 1971 G errnany ..P 21 06 964.7

[52] US. Cl 102/78, 102/80, 102/81 [51] Int. Cl. F42c 15/24 [58] Field of Search 102/70, 76, 77, 78, 102/79, 80, 73, 49.6

[56] References Cited UNITED STATES PATENTS 2,969,737 1/1961 Bild 102/70 R 1,951,444 9/1960 Hunt. Jr. et a1..... 102/78 2,918,870 12/1959 Meister 102/496 2,926,609 3/1960 Van Goey et a1 102/78 X Primary Examiner-Samuel W. Engle Attorney-Paul M. Craig. Jr. et a1.

[57] ABSTRACT In projectiles it is desirable to prevent premature detonation of the explosive charge and therefore the detonating cap is provided in a rotor which is turned from a safety position to a detonating position by spring means after operation of a safety chain comprising several safety components including a first component comprising two interdependent inertia bolts, a second component released by the first component, and a third component constructed as a gas pressure safety device, the second and third components being operatively connected with the rotor such that premature release of one of the components blocks rotation of the rotor into the detonating position. A selfcontained disc-shaped construction housing all the safety components is provided for attachment to a projectile.

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DETONATING CAP SAFETY DEVICES This invention relates to a detonating cap safety device for projectile detonators, with a safety chain consisting of several safety components, released in predetermined manner one after the other after firing the detonating cap, which is provided in a rotor, being turned from the safety position into the detonating position by means of spring force.

Detonating cap safety devices of this type for projectiles have stringent safety requirements, because despite careful manufacture and assembly, occasionally a premature detonation of the projectile occurs, in that due to impact, vibrations, spring fracture or other causes, the rotor containing the detonating cap is released.

Therefore it is an object of the invention to improve the reliability of such detonating cap safety devices and to provide an arrangement of the individual safety components and their method of operation such that any unintentional detonation is prevented. In itself it presents no difficulty to provide a detonating cap safety device with three or more safety components, however it is always a problem to arrange the safety components within a minimum of space, since additional space is not generally available. Further, due to the incorporation of additional safety components additional sources of error may occur to further jeopardize the intended reliability. It is therefore the object of the invention, taking into consideration the aforesaid requirement, to provide a detonating cap safety device with a comparatively low space requirement.

According to the invention, there is provided a detonating cap safety device for projectile detonators, with a safety chain consisting of several safety components, released in pre-determined manner and sequence after firing, wherein the detonating cap is provided in a rotor which can be turned from a safety position into a detonating position by means of spring force, and wherein the safety chain comprises a first safety component including two inertia bolts operating interdependently, a second safety component released by thefirst safety component, and an independent third safety component constructed as a gas pressure safety device, the second and third safety components being located opposite each other and in operative connection with the rotor in such a way that when there is a premature release of one of the safety components, the rotation of the rotor into the detonating position is blocked.

The detonating cap safety device in accordance with the invention is suitable both for rotated projectiles and for unrotated projectiles, such as rocket projectiles, and the gas-pressure safety device as well as its effective coupling to the other safety components gives maximum safety, since the gas pressure safety device allows a simple and reliable construction.

The use of the gas pressure safety device is particularly appropriate in a detonating cap safety device for the detonator of a rocket projectile, in which a second propulsion charge, i.e. a sustainer, is provided. In this case, the gas pressure necessary for the final release is developed by the burning-off of the propulsion charge, by which means it is guaranteed that the detonating system becomes live only after the projectile has reached a significant safety distance from the firing point, which is of particular advantage, if the firing has to take place over ones own armed forces.

The operational reliability of the safety components and their operative interdependency are advantageously promoted in that all the safety components as well as the rotor containing the detonating cap are located in a substantially disc-shaped housing. In this manner the detonating cap safety device forms a selfcontained component of small external dimensions due to which even the manufacture of the projectile and the associated detonators is simplified.

In accordance with the invention the gas pressure safety-device comprises a punch guided in a bore of the housing, which punch lies against a membrane provided in the bore and supports a locking ball which locks the rotor in its safety position the arrangement being such that when the propulsion charge gases act on a piston having the same axis as the punch and a predetermined gas-pressure is reached, the membrane is ruptured and after the release of the locking ball, the rotor is rotated by its drive spring into the detonating position. This method of construction facilitates particularly small dimensions, so that this safety device can be provided without any additional space requirement in the disk-shaped housing.

In a further advantageous embodiment of the invention the second safety component comprises a pin, located on an arm pivotally mounted on the housing, which arm is released by the first safety element, and which pin engages in a slot provided in the end of the rotor at right angles to its axis of rotation in such a way that when there is a premature release of the gas pressure safety device a rotation of the rotor into the detonation position is prevented by the locking of the pin in the slot. This construction also contributes to the possibility of a space saving construction, in that the arm has a curved shape and is adapted to follow the substantially circular peripheral surface of the housing.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is an exploded view of a detonating cap safety device, in accordance with the invention,

FIGS. 2 and 3 respectively show the inertia safety device before and after firing,

FIGS. 4 and 5 respectively show the gas pressure safety device before and after the release of the rotor supporting the detonating cap (shown displaced).

The detonating cap safety device with a safety chain, comprising the safety components A, B and C illustrated in FIG. 1, is located in a substantially circular disc-shaped housing 1 and forms with the latter a selfcontained unit D, which can be inserted at the appropriate place into a projectile. In the housing 1 a rotor 3 supporting the detonating cap 2 is also rotatably provided.

The safety component A forms a firing safety device comprising two inertia bolts 4 and 5, which is only released by a firing acceleration of pre-determined magnitude and duration acting in the direction of the arrow P. The inertia bolt 5 is arranged to slide parallel to the axis of the projectile in a socket 6 in the housing I and in its front or safety position is held by a spring 7 located in the socket, the bolt being supported at a conical surface 8 formed on its front end by a collar 9 formed by crimping the end of the socket. The inertia bolt 4 is arranged parallel to the bolt 5 in a bore 10 of the housing. The bolt 4 is supported against a spring 11 arranged in the bore 10 and is held in its safety position by a ball 12, which is located in a bore 13 connecting the bore to the socket 6. In the safety position shown in FIG. 2, the ball 12 engages in a peripheral groove 14 provided in the bolt 4.

A pin 15 provided at the front end of the inertia bolt 4, locks a curved arm 16 in the safety position according to FIG. 2, which arm 16 is the same shape as the substantially circular peripheral surface of the housing and is pivotally mounted to the housing 1 by means of a lug 17 and a pin 18. In the swinging direction the arm 16 is acted upon by a fastening spring 19, which is engaged in a slot 20 in the housing.

A bore 21 provided in housing 1 at right angles to the longitudinal axis of the projectile accommodates a rotor 3 supporting a detonating cap 2. In the detonating position the detonating cap can be detonated in known manner by electric contact or by means of a primer 7 through a recess 22 in the front side of the housing. In the safety position the rotor is rotated about its longitudinal axis, so that the detonating cap is not in the vicinity of the recess 22. In this position the rotor 3 is retained by two members B and C working independently. One of them comprises a pin 23 provided on the inner side of the arm 16, which pin engages in a slot 24 provided on the front end of the rotor, and eccentric to the axis of rotation of the rotor. At the other end of the rotor there is provided a worm gear 25, which engages with a worm 26 mounted in the housing. The drive of the worm comprises a taut coil spring 27, which is located in a spring cap 28 connected to the end of the housing.

The safety member C is the gas pressure device illustrated in FIGS. 4 and 5. With a view to greater clarity, in FIG. 1 the arrangement of the gas pressure safety device C has been shown displaced through l80. In a bore 29 provided at right angles to the longitudinal axis of the rotor 3 in the housing 1 there is located a membrance 30 supported against a shoulder, which membrane is secured by a sleeve 31, which terminates at its outer end at the surface of the housing and is fixed to the housing by appropriate means (e.g. centre punch marks). In the same way a two-part punch 32 is retained in the sleeve 31, the punch parts having a helical spring 33 therebetween so that one of the parts lies against the membrane 30. The punch 32 supports a locking ball 34 which retains the safety position of the rotor 3.

At a suitable place in the projectile, for example in the projectile base 35, in a bore 36 having the same axis as the bore 29, a piston 37 provided with a sealing ring is slidably mounted and is retained by a spring circlip 38. FIG. 4 shows the installed position of the piston 37, in which a push-rod 37a provided on the piston reaches to immediately in front of the punch 32.

The method of operation of the described detonating cap safety device is as follows. Before firing, the inertia bolts 4 and 5 are located in the position shown in FIG. 2. The arrangement is such that only an acceleration force P of pre-determined magnitude and duration is able to bring about the released position as shown in FIG.3, since the movement of the bolt 4 can take place only when the bolt 5 has reached its (in the drawing) lower position and the continuing acceleration force also brings about the movement of the bolt 4 into the position as shown in FIGS, after the locking ball 12 has moved out of the peripheral groove 14. In this position a spring clip 4a secured in the wall of the housing engages a shoulder of the bolt 4 to retained bolt 4. Due to the displacement of the bolt 4 the arm 16 is released, which swings out under the action of the fastening spring 19 acting upon it. (In rotated projectiles the fastening spring 19 is not necessary; the swinging out of the arm is effected by centrifugal force).

After a predetermined gas-pressure acting on the piston 37 of the gas-pressure safety device has been reached which is produced either by the firing pro pellent charge or by a sustainer charge the push-rod 37a strikes against the punch 32, by which means the membrane 30 is ruptured and due to the compression spring 33 an intermediate space 320 occurs between the two parts of the punch (FIG.5). The locking ball 34 can now move into this intermediate space as a result of the rotary force acting on the rotor 3 due to the coil spring 27 by way of the worm drive, so that the rotor is turned into its ignition position.

The safety components A, B and C are associated with the rotor 3 to be protected such that the latter can only be rotated into the detonation position, if the safety elements are released in the time sequence described. If, for example, the gas pressure safety device C should be released before the other safety elements, then the force of the coil spring 27 allows the rotor to rotate by an amount of approximately 15, however a further rotation is prevented by the pin 23 provided on the arm 16. Due to the force of the coil spring 27 the pin 23 is retained in the slot 24 of the rotor and locks it. Thus detonation of the detonating cap located in the rotor is not possible. The reliability of the locking can be further increased if the walls of the slot 24 and the pin have corresponding back tapers.

What is claimed is:

1. A detonating cap safety device for projectile detonators, comprising a housing, a rotor arranged within the housing and rotatable into a detonating position within the housing, drive spring means for rotating the rotor into the detonating position, and safety chain means for controlling the rotation of the rotor into the detonating position in accordance with a predetermined sequence of firing, said safety chain means including a first safety means having at least one inertia bolt arranged within a bore of the housing and movable from a first to a second position in response to a predetermined inertia force, a second safety means including an arm member pivotally connected with the housing and having pin means engaging a portion of the rotor in a first position thereof for limiting the rotation of the rotor, said arm member being pivotally movable from the first position in response to the movement of said at least one inertia bolt to a second position in which the pin means disengages from the rotor, and a third safety means including a gas-pressure safety means arranged within a bore of the housing, said gas-pressure safety means including a locking member engaging a portion of the rotor to prevent the rotation thereof, said locking member being movable from the engaging position to a disengaged position in response to a predetermined gas pressure such that said rotor is rotated into the detonating position thereof by said drive spring means upon release of said first, second and third safety means in sequence, said second and third safety means being engaged with said rotor so as to prevent rotation of said rotor into the detonating position when there is a premature release of one of the safety means.

2. A detonating cap safety device according to claim 1, wherein said rotor is provided at an end thereof with a slot extending at right angles to the axis of rotation of said rotor, said pin means of said second safety means engaging said slot of said rotor so as to prevent rotation of said rotor into the detonation position upon premature release of said third safety means.

3. A detonating cap safety device according to claim 2, wherein said housing has a substantially circular peripheral surface and said arm member of said second safety means has a curved shape adapted to follow the substantially circular peripheral surface of the housing.

4. A detonating cap safety device according to claim 2, wherein said first safety means includes first and second inertia bolts arranged within bores in the housing and operating interdependently of one another for movement from a first to a second position in response to the predetermined inertia force.

5. A detonating cap safety device according to claim 4, wherein said housing is substantially disk-shaped and said safety chain means and said rotor are located in said housing thereby forming a self-contained component.

6. A detonating cap safety device according to claim 5, wherein said gas-pressure safety means includes punch means disposed in a bore of the housing, a membrane in said bore preventing movement of the punch means through the bore in a first position of the punch, said member engaging a portion of the rotor to prevent rotation thereof being a locking ball supported by said punch means in the first position thereof, said punch means being responsive to the propulsion charge gases attaining the predetermined gas pressure for rupturing the membrane to permit movement of the punch means from the first position thereof and to release said locking ball enabling the rotor to be rotated into the detonating position thereof.

7. A detonating cap safety device according to claim 1, wherein said first safety means includes first and second inertia bolts arranged within bores in the housing and operating interdependently of one another for movement from a first to a second position in response to the predetermined inertia force.

8. A detonating cap safety device according to claim 1, wherein said housing is substantially disk-shaped and said safety chain means and said rotor are located in said housing thereby forming a self-contained component.

9. A detonating cap safety device according to claim 1, wherein said gas-pressure safety means includes punch means disposed in a bore of the housing, a membrane in said bore preventing movement of the punch means through the bore in a first position of the punch, said member engaging a portion of the rotor to prevent rotation thereof being a locking ball supported by said punch means in the first position thereof, said punch means being responsive to the propulsion charge gases attaining the predetermined gas pressure for rupturing the membrane to permit movement of the punch means from the first position thereof and to release said locking ball enabling the rotor to be rotated into the detonating position thereof. 

1. A detonating cap safety device for projectile detonators, comprising a housing, a rotor arranged within the housing and rotatable into a detonating position within the housing, drive spring means for rotating the rotor into the detonating position, and safety chain means for controlling the rotation of the rotor into the detonating position in accordance with a predetermined sequence of firing, said safety chain means including a first safety means having at least one inertia bolt arranged within a bore of the housing and movable from a first to a second position in response to a predetermined inertia force, a second safety means including an arm member pivotally connected with the housing and having pin means engaging a portion of the rotor in a first position thereof for limiting the rotation of the rotor, said arm member being pivotally movable from the first position in response to the movement of said at least one inertia bolt to a second position in which the pin means disengages from the rotor, and a third safety means including a gas-pressure safety means arranged within a bore of the housing, said gas-pressure safety means including a locking member engaging a portion of the rotor to prevent the rotation thereof, said locking member being movable from the engaging position to a disengaged position in response to a predetermined gas pressure such that said rotor is rotated into the detonating position thereof by said drive spring means upon release of said first, second and third safety means in sequence, said second and third safety means being engaged with said rotor so as to prevent rotation of said rotor into the detonating position when there is a premature release of one of the safety means.
 2. A detonating cap safety device according to claim 1, wherein said rotor is provided at an end thereof with a slot extending at right angles to the axis of rotation of said rotor, said pin means of said second safety means engaging said slot of said rotor so as to prevent rotation of said rotor into the detonation position upon premature release of said third safety means.
 3. A detonating cap safety device according to claim 2, wherein said housing has a substantially circular peripheral surface and said arm member of said second safety means has a curveD shape adapted to follow the substantially circular peripheral surface of the housing.
 4. A detonating cap safety device according to claim 2, wherein said first safety means includes first and second inertia bolts arranged within bores in the housing and operating interdependently of one another for movement from a first to a second position in response to the predetermined inertia force.
 5. A detonating cap safety device according to claim 4, wherein said housing is substantially disk-shaped and said safety chain means and said rotor are located in said housing thereby forming a self-contained component.
 6. A detonating cap safety device according to claim 5, wherein said gas-pressure safety means includes punch means disposed in a bore of the housing, a membrane in said bore preventing movement of the punch means through the bore in a first position of the punch, said member engaging a portion of the rotor to prevent rotation thereof being a locking ball supported by said punch means in the first position thereof, said punch means being responsive to the propulsion charge gases attaining the predetermined gas pressure for rupturing the membrane to permit movement of the punch means from the first position thereof and to release said locking ball enabling the rotor to be rotated into the detonating position thereof.
 7. A detonating cap safety device according to claim 1, wherein said first safety means includes first and second inertia bolts arranged within bores in the housing and operating interdependently of one another for movement from a first to a second position in response to the predetermined inertia force.
 8. A detonating cap safety device according to claim 1, wherein said housing is substantially disk-shaped and said safety chain means and said rotor are located in said housing thereby forming a self-contained component.
 9. A detonating cap safety device according to claim 1, wherein said gas-pressure safety means includes punch means disposed in a bore of the housing, a membrane in said bore preventing movement of the punch means through the bore in a first position of the punch, said member engaging a portion of the rotor to prevent rotation thereof being a locking ball supported by said punch means in the first position thereof, said punch means being responsive to the propulsion charge gases attaining the predetermined gas pressure for rupturing the membrane to permit movement of the punch means from the first position thereof and to release said locking ball enabling the rotor to be rotated into the detonating position thereof. 